The Sun is a star, a hot glowing ball of gas that is in the heart of our Solar System. It is a star and not so round. The Sun is in the center of our Solar System and takes up 99.8% of the mass of the entire Solar System. It has a diameter of about 1392684 km, around 109 times the diameter of the Earth and has a mass that is 330000 times the mass of the Earth. That very colossal mass of the Sun is 19891000000000000000000000000000 kg. About three quarters of the Sun's mass consists of hydrogen, and the rest is mostly helium. The temperature at the Sun's core is about 15 million degrees Celsius. The Sun does not have any rings. Since the Sun is not a solid body, different parts spin at different rates. At the equator , the Sun spins once every 25 Earth days, but at its pole it rotates once on its axis every 36 Earth days. A day on the Sun is about as long as 25.38 Earth days, (609.12 hours.) The Sun is 4.6 billion years old and still counting.